You currently have javascript disabled. Several functions may not work. Please re-enable javascript to access full functionality.

Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!

Say hello and join the conversation

Subscribe to topics and forums to get automatic updates

Get your own profile and make new friends

Classifieds with all sorts of Subaru goodies

Photo hosting in our gallery

Meet other cool people with cool cars

Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning** Not an actual guarantee, but seriously, you probably won't regret it!

How to diagnose a plugged cat. converter?

So, how do you diagnose a plugged catalytic converter? I've heard of them being plugged, but how do know that's the problem? I'm trying to figure out why my '86 carbed GL Wagon is so low on power. I had a leaky vacuum advance actuator, fixed that, now it pings a little but doesn't really accelerate much better.

The car sat in the back yard for 3 years, so the carb might be in bad shape, but it runs smooth, just not much power.

well if you suspect the cat remove the y pipe wit the cat in it and go for a drive and see if it has power if it has you know you need it replaced if it still hasnt got power theres somethin else

thas the only way i know of withont special gadets

PS is the fuel the stuff thats been sitting for 3years?

The old fuel is gone by now, plus a can of Seafoam has been run through the fuel tank. I suppose I should probably replace the fuel filters too, the more I read about them/it, I have no idea when those have been changed.

you can test with vacum or pressure, either uses a low cost vacum/fuel pressure gauge. DO NOT use this gauge for testing fuel pressure on a fuel injected car. gauge normaly reads between 25" of vacum and 10# of fuel pressure, to test using vacum hook the gauge to manifold vacum, below the carb, or throttle body, engine warm, idle check vacum, should be more than 15" if the vacum drops as the engine is idling steady than there might be a restriction in the exhaust, to test using pressure you remove an o2 sensor or drill a small hole in the pipe ahead of the cat, for the o2 hole drill a hole in a small superball hook your tester hose to the superball and hold it against the bung, have a friend rev the engine and let off, the pressure should not go over 2#, the exhaust is very hot, dont get burnt. converters can meltdown, sending converter parts down the exhaust system so replacing a bad converter may not fix a prob w/ restricted exhaust, you can test the other parts the same way by drilling holes after the cat after bends, etc, drill or use self tapping screws so that you can seal the holes. sorry so longwinded but good luck:eek:

Mine will still get it up to 80, but it takes awhile. Can't pull I-5 hills in 5th, that's the part that bugs me.

Monte

If the cat is plugged, it won't make a difference whether you're in 5th or not. If it has enough power to pull the hill in a lower gear, the cat is probably OK. The feedback systems in these cars are notorious for leaning out the mixture too much and killing power. They lack the sophistication of today's systems and overcompensate to the lean side by creating vacuum leaks rather than precisely meter the fuel mixture. Combine that with an engine that doesn't have a lot of torque at low speed and you can understand why you have to downshift on a big hill. If you can find a steel ball of the right size, you can put it in the main vacuum hose that leads to the air suction devices and fool the smog police. Just take the ball back out to pass your emissions test.

whatever you do, don't take the muffler shop's word for it... I had 2 shops, one Mineke and one small local one, both tell me they thought my catalytic converter was clogged... of course it's $250 and plenty of labor for them to put a new one in for you...

after a tune-up (and Superior Import Repair attaching the rest of the exhaust for me) it ran awesome and passed emisions with no problems...

and it you're going to just remove it to see if that helps make sure you don't drive it too far, or coast fast down a steep hill... you don't want that cold air getting back up in there if you don't have anything coming off the heads...